This invention relates to fuel compositions having improved low temperature characteristics. More particularly, this invention relates to compositions comprising distillate hydrocarbon fuels having minor amounts sufficient to improve cloud point, pour point and filterability of diesel and heating fuels of an additive prepared from the reaction products of a long chain oligomeric alkylsuccinic anhydride, a higher alkyl linear saturated alcohol and a tertiary amino substituted polyol.
As is well known to those skilled in the art, diesel fuels and the like present problems at low temperatures because of poor flow characteristics and clogging of fuel filters. Consequently, there is a continuing need for more efficient means for solving these low temperature problems. The materials described herein, when added to such fuels, improve their low temperature filterability and flowability characteristics.
Although many lubricant and fuel additives have been described from various alkylsuccinic anhydrides and their esters, applicants have discovered that effective products for improving low temperature properties of diesel fuels and the like can be made from specific combinations of raw materials within a limited molecular weight range comprising an alkylsuccinic anhydride, an aliphatic alcohol and a polyhydroxy tertiary amine.
U.S. Pat. No. 4,108,613 teaches the use of a mixture of (1) the reaction product and an epoxidized alpha-olefin with a nitrogen-containing compound selected from ammonia, an amine, a polyamine or a hydroxyamine and (2) an ethylene-olefin copolymer as an additive to depress the pour point of hydrocarbonaceous fuels and oils.
U.S. Pat. No. 3,962,104 discloses lubricating oil compositions containing minor amounts of quaternary ammonium salts useful as oil improving additives wherein the quaternary ammonium salts utilize a cation derived from the reaction product of a tertiary amine with an olefin oxide and water. None of these prior art materials, however, use the specific combination of raw materials disclosed herein.
Unlike prior art such as U.S. Pat. No. 3,117,937, the esters of this invention contain acyl groups derived from complex acids which are the mixed ester-carboxylic acid reaction products from an alkylated succinic anhydride and a monoalcohol. The initial reactant for introducing the acyl fragment is an anhydride. These acyl groups contain a minimum of 44 carbon atoms (at least 28 from the anhydride fragment, and at least 16 from the monoalcohol fragment), and when used at the appropriate levels in distillate fuels, impart unique improvements in the cloud point and the filterability temperature of the resulting fuel compositions.
One object of this invention is to provide an additive product which will operate to lower the cloud point and the pour point of hydrocarbon fuels and improve their filterability.
A further object of this invention is to provide a facile process for preparing these additive products.